2004 Astro Van starting trouble.

I have an intermittant problem starting in cool damp conditions. If it doesn't start right away I cannot get the vehicle started. The only solution I have found is to disconnect the battery for at least 24 hours. When I reconnect the battery the vehicle starts immediately.

I am convinced the ECM is bad but I cannot convince anyone at a shop of this. Of course everything they have done to fix it has not worked. I am done with the shops! I'll fix it myself.

Is there a quicker way to reset the ECM without disconnecting the battery for 24 hours?

Well it wan't the ECM afterall, my bad. It was the cam shaft position sensor inside the distributer cap. As it began to get cool and damp again, it started acting up. On advice from a friend I took a blow dryer and started aiming it at sensors until I found one that made the van start.

First, it is EXTREMELY rare for an ECM to go bad. Second, disconnecting the battery does NOT reset the OBDII system. The use of a scan tool is the only way to reset it.

Is the SES light on? Have you retrieved DTC's? If so what order were they in and what were the DTC's? How many miles, and how much time is on the spark plugs, distributor cap, rotor, and spark plug wires? Have you checked fuel pressure and leakdown? If so what were the results? If you have replaced parts, what were they and what brand?

Reset might be the wrong word, but it clears out all the sensor error data because when I took it in they told me the data was cleared out from having the battery disconnected. Clearing this data MUST have something to do with it.

The check engine light does come on, but after my work around disconnecting the battery, the check engine light is off again.

This problem only occurs when temperatures are near the freezing point and damp (ie. raining or snowing). The vehicle starts fine in very cold weather (-20) and all summer long.

Fuel pressure is fine.

If it was the distributor, spark plugs, or any other mechanical item like the fuel pump or filter, why would my work around work? just leaving the vehicle sit for days with the battery connected does NOT work. The battery MUST be disconnected for at least 24 hours in order to get it started again.

The vehicle has 220,000 miles on it. When it starts, it runs great. It never hestitates or misses.

Disconnecting the battery clears the short term memory and will turn the SES light off. However, when you reconnect the battery and turn the ignition back on, the ECM runs a self test. If there are any "hard faults" it will turn the SES light back on immediately. After the engine is running, the ECM runs several different monitors, (tests) of various circuits. As the parameters are met for each monitor, and the tests complete, if the test fails, the SES light will come back on and a DTC will be set in the history file. Disconnecting the battery for ANY length of time will not erase DTC's that are set in the history file, they are "burned" into memory. The reason it's designed like this is in the event of a power failure to the ECM, the technician can still access the history file and retrieve the DTC's for diagnosis. The only way to clear the history file is with a scan tool.

What I would suggest is have the DTC's retrieved. (Autozone will do it for free) Have the tech make sure all of the I/M readiness tests, (monitors), are complete before retrieving the DTC's. If they are not complete, drive the vehicle until they are. Then post the DTC's here in the order they were retrieved. This might give a clue that will help with diagnosis.

Also, how many miles are on the spark plugs, distributor cap, rotor, and spark plug wires? What brand of parts are they? (the 4.3L is very fussy on certain parts) You mentioned that "fuel pressure is fine", what is the fuel pressure and how long does it hold?

The main point here is that the 24 hour theory with electric off is BS-- the ECM would never intentionally create a "NO START" condition. and if it did it would tell you why....

sounds a whole lot like an ignition module, or crank sensor problem-- get the codes to us like stated above- and we'll go from there....